The properties are quite simple here. The type property indicates the type of address represented by the object (work, home, and so forth). Since the plural property is true, multiple types can be specified. This allows an address to be marked as being, for example, a work address for receiving parcels.

The street-address property is plural as well. This allows multiple lines of address information to be contained in the street-address array.

The microformat is registered with the microformat API by calling Microformats.add(), like this:

Microformats.add("adr", adr_definition);

Note: To be clear: since the adr microformat is included by default in Firefox 3 and later, you don't need to add it yourself if you wish to make use of it.